1. Field
This application relates to products, such as flood sources, that are used to calibrate radiation detection devices, such as gamma cameras.
2. Background of Related Art
Radiation detection devices, such as gamma cameras, often require testing and/or calibration to ensure that their sensitivity is uniform over the area that they detect. Devices that produce a uniform cross-section of radiation, such as a flood source, are commonly used for this purpose.
A flood source typically includes a flat surface, such as a sheet of paper, on which radioactive isotopes are printed. For obvious safety and other reasons, paper that has been impregnated with radioactive isotopes must be readily identifiable as having an active area.
One approach for achieving this has been to mix a radioactive isotope solution with ink before it is printed on the paper, such as is described in U.S. Pat. No. 7,172,799, the entire content of which is incorporated herein by reference. The ink in the active area on the paper remains visible after the mixture is printed, thus signaling that the paper has an active area and where it is.
Mixing ink with the radioactive isotope solution, however, may adversely affect the uniformity of the isotope in the solution. This approach may also require a substantial amount of ink, which may be costly.